Flying Into The Mouth Of The Beast: NASA Uses UAVs To Study Volcanic Plumes

Last month, Earth science researchers from NASA traveled to Turrialba Volcano near San Jose, Costa Rica. The research team was there to study the chemical environment of the volcano by flying a Dragon Eye unmanned aerial vehicle (UAV) into the sulfur dioxide plume and over its summit crater. The UAV — a small electric aircraft equipped with cameras and sensors — will help the scientists improve the remote-sensing capabilities of satellites and computer models of volcanic activity.

Ten flights were launched between March 11 and 14, 2013, sending the UAV into the volcanic plume and along the rim of the Turrialba summit crater, which is approximately 10,500 feet above sea level (ASL). The Dragon Eye was launched from a site at 8,900 ASL and flights ranged over 2,000 feet over the summit, to about 12,500 ASL. The objectives for the study included improving satellite data research products, such as maps of concentration and distribution of volcanic gases, and transport-pathway models of volcanic plumes.

Data from the UAV flights was coordinated with the Advanced Spaceborne Thermal Emission and Reflection (ASTER) instrument aboard NASA’s Terra spacecraft. This allowed the scientists to compare sulfur dioxide concentration measurements from the satellite to those taken from directly within the plume by the UAV. Computer models created as a result of this study will contribute to safeguarding the National and International Airspace System, improve global climate predictions, and mitigate environmental hazards, such as sulfur dioxide volcanic smog or “vog,” for people who live around volcanoes.

The intensity and character of the volcanic activity near the eruption vent is a key factor of such models. For any model that predicts the direction of the volcanic plume, for example, knowing the height of ash and gas concentrations, and temperatures over the vent during an eruption, are important initial factors.

“It is very difficult to gather data from within volcanic eruption columns and plumes because updraft wind speeds are very high and high ash concentrations can quickly destroy aircraft engines,” said David Pieri, the project´s principal investigator and a research scientist at NASA´s Jet Propulsion Laboratory (JPL). “Such flight environments can be very dangerous to manned aircraft. Volcanic eruption plumes may stretch for miles from a summit vent, and detached ash clouds can drift hundreds to thousands of miles from an eruption site.”

UAVs, especially those with electric engines that ingest little contaminated air, are an emerging and effective way to penetrate such dangerous airspace in the search to gather crucial data about ash and gas concentrations and their lateral and vertical distribution.

Scientists from NASA’s Ames Research Center used three Aerovironment RQ-14 Dragon Eye UAVs acquired from the United States Marine Corps (USMC) through the General Services Administration. The small electric unmanned aircraft, which weigh 5.9 pounds, have a 3.75-foot wingspan, and carry twin electric engines, are able to carry a one-pound instrument payload for up to an hour inside the volcanic plume.

“This project is great example of how unmanned aircraft can be used for beneficial civilian purposes — in this case for better understanding Earth system processes and the impact of volcanism on our atmosphere,” said Matthew Fladeland, airborne science manager at Ames. “By taking these retired military tools, we can very efficiently and effectively collect measurements that improve NASA satellite data and aviation safety.”

Payload instruments were integrated onto the UAV, including the standard USMC visible and infrared video cameras, sensors for sulfur dioxide and particles, and automatic atmospheric sampling bottles keyed to measure sulfur dioxide concentration. The UAV was directed into a volcanic plume to characterize its chemical and physical environment, which became especially important during simultaneous flights by NASA’s Terra spacecraft carrying the ASTER imaging radiometer.

Next year, the Ames scientists plan to operate the larger SIERRA unmanned aircraft, with a 400 pound takeoff weight with 100 pound payload. SIERRA will carry a more sophisticated mass spectrometer to measure additional gases in the Turrialba volcano plume.

To test and develop these UAVs, the volcanoes of Costa Rica provide excellent natural laboratories. Turrialba’s continuously erupting plume, for instance, has relatively minimal updraft and wind shear and consists primarily of carbon dioxide, water vapor, sulfur dioxide, some hydrogen sulfide and other minor gases, such as helium, and sulfate nano-particles at altitudes up to about 11,000 feet ASL. Commercial and private air traffic is very low in the airspace around and over Turrialba as well.

Sampling drifting ash and gas in volcanic plumes up to 30,000 feet ASL that result from large explosive eruptions such as those that crippled aviation traffic in Iceland and Europe in the spring of 2010 is a long-term project goal.